单项选择题
A.It describes the reachability of routes in stub areas.
B.It describes the reachability of routes in totally-stubby areas.
C.It describes the reachability of routes in not-so-stubby areas.
D.It describes the reachability of routes in partially-stubby areas.
多项选择题 WhichthreeauthenticationoptionsdoesIS-ISsupport？（）
多项选择题 WhichfourcomponentsmakeuptheNetworkEntityTitle（NET）ofanIS-ISrouter？（）
单项选择题 RoutersAandBareconnectedwithapoint-to-pointOC-3interface.Eachrouter’sOC-3interfaceisconfiguredforbothLevel1andLevel2.Theroutersareconfiguredindifferentareas.HowmanyIS-ISadjacenciesexistbetweenthetworouters？（）